Before anyone came in and criticizes Berryz with low sales and relate this concert with C-ute's success, I would like to remind people,
Tokyo Girls Style went to Budoukan once and their highest selling single to that point was around 12,000+. They released a single after that, on 17/10 entitled Road to Budoukan 2012 ~Bad Flower~ which sold 26, 986 copies, became their highest selling single and only after the Budoukan concert, the group received mainstream attention. The later single sold 23,000+ copies and if I'm not mistaken, they already planned to perform once again in Budoukan this december. Right now, everybody know Tokyo Joshiryuu, and this group even appeared in Malaysia's tv program (though, they appeared before performing at Budoukan)
Meanwhile, Berryz last single, Golden Chinatown/Sayonara Usotsuki Watashi sold 31,000+ in their first week. Currently situation, performing in Budoukan doesn't mean you're the most hardworking, offering highly selling singles and most-powerfully-magnificent-undeniable idol group, but instead, it became a huge milestone for them to become more serious and receive many attentions. They receive the Budoukan not because of anybody else, not because another groups' success, not because another group's help... They receive the Budoukan because anybody can hold a concert there and it is time to make the members realize their dreams back and they're reaching 10th anniversary.